Multiphoton microscopy for tumor regression grading after neoadjuvant treatment for colorectal carcinoma

Figure 1 Representative multiphoton microscopy images from a muscularis propria specimen, color-coded green represents the second-harmonic generation signal and color-coded red corresponds to the two-photon excited fluorescence signal. After neoadjuvant radiochemotherapy, predominant fibrosis changes can be seen with minimal inflammatory cells replacing tumor cells. A: Multiphoton microscopy of second-harmonic generation from collagen; B: Two-photon excited fluorescence of collagen, elastin, inflammatory cells, and blood vessels; C: Overlay image (scale bar: 100 μm); D: Hematoxylin and eosin staining of an adjacent section (magnification × 40). The tumor underwent complete regression and was replaced by fibrous tissues (blue arrows). Blood vessel hyperplasia is denoted with a white arrow. Muscular tissue is denoted with a pink arrow.